Mutations 2

Question 1

What is a heterozygous mutant

Answer 1

One that contains both the wild allele and another (B/b)

Question 2

Name two recessive mutation diseases

Answer 2

Albinism
Phenylketonuria

Question 3

How many gene combinations are available to give different forms of albinism

Answer 3

4

Question 4

within albinism what causes the phenotype changes

Answer 4

there is not enough of the product (melanin) which makes them more prone to skin cancer

Question 5

what is phenylketonuria

Answer 5

a progressive brain dysfunction disease caused by a recessive gene

Question 6

what causes the phenotype within phenylketonuria

Answer 6

there is too much of the substrate (phenylalanine) and due to the dysfunctional enzyme this cannot be converted to the product

Question 7

what are the two ways in which a recessive mutation can affect the phenotype

Answer 7

too much substrate
not enough product

Question 8

what is the mutant allele x- always recessive to

Answer 8

the wild type allele X+ (the wild type allele is the most common gene in the population)

Question 9

what determines dominance/recessivity within a gene

Answer 9

how the pool of product (usually a protein) encoded by the two alleles functions within a heterozygote

Question 10

wild type allele + other allele determines what…
whereas the protein pool determines …

Answer 10

genotype
phenotype

Question 11

most recessive mutations are a …

Answer 11

loss of function (therefore most loss of function mutations are recessive)

Question 12

most dominant mutations are a …

Answer 12

gain of function

Question 13

what are the two ways for a incomplete dominance gene to occur

Answer 13

-having one mutant allele is enough to not be normal (in a heterozygote)
-having two mutant alleles is worse or different again (in a homozygote)

Question 14

what are the two ways in which a dominant mutation will change function

Answer 14

-more of a normal function (eg. more enzyme activity)
-new function (unrelated to the original)

Question 15

name of form of autosomal dominant mutation

Answer 15

achondroplasia (dwarfism)

Question 16

how does achondroplasia (dwarfism) get caused by a dominant mutation

Answer 16

FGFR3 normally inhibits bone growth however within dwarfism it has inhibited it too much to the point that bones dont fully develop

Question 17

what percentage of those with achondroplasia have a parent also with the disease

Answer 17

20% (80% of mutations are from the parents germline and so are de novo)

Question 18

name a progressive neurodegeneration disease caused through a dominant mutation

Answer 18

huntingtons disease (autosomal dominant mutation)

Question 19

what are the two ways pharmacology can tackle a dominant and recessive mutation

Answer 19

-develop an agonist (activator)
-develop an antagonist (inhibitor)

Question 20

are most mutations generally dominant or recessive

Answer 20

recessive (only show in the phenotype as homozygotes)

Question 21

what determines if a mutation will be recessive or dominant

Answer 21

the behaviour of the heterozygote (which allele will remain from the B/b heterozygote)

Question 22

define allele

Answer 22

the alternative form or variations of a gene